Car won't start after 2 days in garage

ANONYMOUS

2005 LEXUS LS 430

90,000 MILES

Car won't start after 2 days in garage. Starts when jumped. New battery. Is there a design flaw with this vehicle that causes the battery to drain so fast. Dealer claims vehicle is o.K. But a dead battery after two nights in the garage is not o.K. To me. What might be the cause?